This activity involves a graph AND QUESTIONS AT THE END!!! Please make sure you scroll all of the way to the bottom of the screen. Your answers should be referenced with background research and the essay should be at least one page. Chart Separate.
In this activity you will be examining the relationship between the variables DO and temperature taken starting at the epilimnion to the hypolimnion in one of the Finger Lakes during the summer. You will graph the data provided and look for a correlation between the two variables. Correlation is measured between +1.0 and -1.0. As the number gets closer to zero the weaker the correlation. Correlations close to +1.0 indicate a strong positive relationship, whereas correlations close to -1.0 indicates a strong negative relationship. An example of a positive correlation would be sun exposure and sunburn – the more sun exposure a person has the more likely that person will get sunburn. An example of a negative correlation would be speed and time. The greater the speed a car drives the shorter the time it takes to get to the destination. Before conducting this activity review how graphing correlations work by visiting the following website: Graphing Correlations. After determining the correlation you will make a scatter chart of the data
To conduct this activity you will need to follow these steps: (Note that actions are in italics ). If you need assistance review the video link in this module for making a scatter chart in excel. Scatter plots are also covered on page 10-11 of the textbook.
- Link to the Lake DO/Temp data set.
- Save the data set onto a disk or your computer.
- In the cell next to DO mg/L type =correl(
- The program will then ask you to define the two array of cells used in the formula (array of cells are the two variables: Do and Temp). To highlight the first array click on the number directly under the word Temp and press CTRL+SHIFT+ARROW Down KEY which selects the column to the last used cell (this appears as array1 in the formula). Type a comma , Click on the number under the word DO and repeat this procedure to select the second array.
- Enclose the formula with the outside bracket “)”.
- You should now have a number between -1.0 and +1.0 in the cell next to your data set – this is the
- In the next few steps we will be making a chart of the data.
- Click on the Temp cell, press shift and at the same time click on the DO cell. Both cells should appear
- Press CTRL+SHIFT+ DOWN ARROW KEY which selects the two columns to the last used cell.
- Go to Insert on menu bar select XY scatter plot.
- Once the chart is made click on Move Chart – far right on menu bar and save the chart as a new sheet – give it a name.
- Under Chart Tools on the menu bar click on Add Chart Element, label the X Axis (horizontal) Temp Celsius and the Y Axis (Vertical) DO mg/l
- In the Chart Title Field Title the chart DO & Lake Temp
- When the graph is finished click on – Trendline on the menu bar (linear). Note: on Office 360 you click on the tab ADD CHART ELEMENT, Trendline
- Save your worksheet.
Submit the graph and an essay that answers the following questions:
A. Is there a strong correlation between DO levels and Temp ? Is it positive or negative?
B. The data for DO and Temp were taken at different depths. What would influence DO levels at the different depths of a lake system?
C. What would influence DO levels in this lake? (note – review chapter on physical attributes of aquatic systems in textbook for ideas and the Water on the Web)
D. These data were collected in the summer months. From the profile of the lake DO and Temp, would you say this lake is eutrophic or oligotrophic? Why?
Graphing Correlations link: https://mste.illinois.edu/courses/ci330ms/youtsey/scatterinfo.html
review the video link : https://www.youtube.com/watch?v=bYf6qO-iBW0
Water on the Web link: https://www.waterontheweb.org/under/lakeecology/index.html
Lake DO/Temp data set. link below.